Two-stage garnet growth in coesite eclogite from the southeastern Papua New Guinea (U)HP terrane and its geodynamic significance

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F19%3A10404595" target="_blank" >RIV/00216208:11310/19:10404595 - isvavai.cz</a>

Result on the web

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=mfkTU_0XJr" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=mfkTU_0XJr</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s00410-019-1612-4" target="_blank" >10.1007/s00410-019-1612-4</a>

Result language

angličtina

Original language name

Two-stage garnet growth in coesite eclogite from the southeastern Papua New Guinea (U)HP terrane and its geodynamic significance

Original language description

Mineral compositions and textures of Late Miocene coesite eclogite from Tomagabuna Island were investigated to constrain P-T conditions during UHP metamorphism and subsequent exhumation. Two stages of garnet growth (core and rim), at eclogite-facies conditions, were documented. In addition to core garnet (I), peak assemblages include omphacite, coesite, phengite, and rutile. Rim garnet (II), amphibole, paragonite, plagioclase, quartz, and accessory biotite and spinel were formed after peak pressure conditions. Although a compositional gradient is present at the core-rim garnet interface, the garnet core has a relatively flat compositional profile, suggesting its crystallization in the coesite stability field. Together with minerals formed subsequent to peak pressure (UHP) conditions, the composition of the garnet rim indicates heating of the eclogite during its decompression into the amphibolite facies mineral stability field. Based on compositional zoning in garnet and application of diffusion modelling, we propose that eclogite-facies metamorphism of the mafic protolith and its host lithologies occurred at, or near, UHP conditions. The core garnet (I) formed at 650 degrees C at 8 Myr in the coesite stability field and was partially resorbed during the onset of exhumation. We infer that garnet rim growth at &lt; 7.1 Ma occurred at P-T conditions corresponding to the boundary between the eclogite and amphibolite facies fields. Diffusion modelling for the garnet core-rim boundary compositions suggests a transient heating event (0.3 Myr) occurred at 1.5 GPa that we infer resulted from heat transport within the Australian-Woodlark plate boundary zone as the coesite eclogite was exhumed. Results caution that apparent P-T paths documented for many UHP terranes may not result from isothermal decompression corresponding to peak temperatures. Instead, paths may link P-T points&apos; set during transient mineral growth events when the UHP rocks form within the subduction channel, and during subsequent heating events, when UHP rocks are exhumed from mantle depths.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10505 - Geology

Project

<a href="/en/project/GA18-03160S" target="_blank" >GA18-03160S: Pre- to syncollisional history of metamorphic rocks in orogenic zone recorded by chemical zoning in garnet; with application to the Bohemian Massif</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2019

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Contributions of Mineralogy and Petrology

ISSN

0010-7999

e-ISSN

—

Volume of the periodical

174

Issue of the periodical within the volume

9

Country of publishing house

DE - GERMANY

Number of pages

16

Pages from-to

73

UT code for WoS article

000506214000002

EID of the result in the Scopus database

2-s2.0-85071290990